Advances in flexible organic electronics enabled development in research areas such as light emitting diodes (LED), transistors, solar cells, and wearable devices. These organic electronics distinguish themselves from their inorganic counterparts by possessing advantages including higher mechanical flexibility, lower gravimetric density, and comparatively lower cost, which are all key factors to the production of conductive electrodes in optoelectronic devices.
Presently, although the active layers and other layers, such as charge carrier transport and blocking layers, can be formed as flexible layers, the required transparent electrode layers are not typically flexible, generally being formed from conducting oxides, such as indium tin oxide (ITO) and fluorine tin oxide (FIO). These materials have shortcomings, in addition to their inherent lack of flexibility, including the limited worldwide resources of indium, acid/base instability, and limited transparency in the near-IR region. Therefore, alternate materials that are highly stable, transparent, and flexible, yet of sufficient electrical conductivity are highly desired. Relatively few conductive oxide replacements have been developed, primarily due to the lack of transparency. Thin potentially flexible, electrically conductive layers with optical transparencies exceeding 70% are rare; for example, 86% transmission has been achieved using carbon nanotubes, Lenshof, et al., Lab Chip 2012, 12, 684, and sheet resistance of 471 Ω/square, Parichehreh et al., Lab Chip 2012 7, 1296. There remains a need to prepare optoelectronic devices with conductive electrodes that are flexible, cheap, and compatible with large-scale manufacturing methods.
As in the case with carbon nanotube, manipulating of particles in suspension is required. Manipulation of particles by applying external stimuli has attracted attention in different fields, especially in lab-on-a-chip applications. Means of manipulating electronic materials include electrokinetic, inertial, magnetophoretic, optical, and dielectrophoretic (DEP). Alternatively, acoustic stimulation allows rapid, gentle, and label-free particle manipulation based on particles' physical properties such as size, density, and compressibility. Advantages of acoustophoresis have been seen recognized in the biotechnology field for cell trapping, cell sorting, and plasmaphoresis. However, acoustic methods are currently limited to flow systems and have not been used to template organic electronic materials. Nevertheless, to this end, an acoustic method of forming an anisotropic film is desirable.